This invention relates to a telephone apparatus, and in particular it relates to a telephone set which may be used for desk operation or wall-mounted operation.
For many years the telephone industry has recognized the desirability of providing a telephone substation apparatus, or more simply, a telephone set, which may be used as a desk unit or a wall unit. A number of designs of telephone sets have been developed which may be used as desk or wall units. The majority of these prior art telephone sets do not convert readily from a desk unit to a wall unit and vice versa. Many of the prior art telephone sets require a tool, such as a screw driver, to change from a desk to a wall unit, and many require the removal, addition or substitution of a part by the subscriber or user of the telephone set.
One such prior art telephone set is descried in U. S. Pat. No. 3,073,911-Mattke et al, issued Jan. 15, 1963. This telephone set has a base with depressions for receiving the transmitter portion and the receiver portion of a telephone handset. The actuator for operating the switching mechanism comprises a pair of spaced apart, cam-shaped plungers which are spring biased to project into the depression for receiving the receiver portion of the handset adjacent the bottom of the depression, that is, adjacent the end of the depression that is closer to the depression for receiving the transmitter portion. Between the spaced apart cam-shaped plungers is a fixed support which has two positions. This support has two arms, a flush arm and a hook arm. In one position the flush arm is flush with the surface between the plungers, that is, it is flush with the surface of the depression for receiving the receiver portion of the handset. In the other position, the hook arm projects between the cam-shaped plungers and conforms substantially to the shape of the projecting parts of the cam-shaped plungers. The fixed support is mounted to the base with a screw, and may be changed from one position to the other by removing the screw, reversing the position of the fixed support, and replacing the screw. When this telephone set is used as a desk unit, the fixed support is in the position with the flush arm outwards. The handset may be positioned on the base with the receiver portion and the transmitter portion of the handset in their respective depressions. The handset is thereby retained and the receiver portion of the handset presses the spaced plungers inwards to operate the switching mechanism. To convert the telephone set for use as a wall unit, the screw fastening the fixed support is removed, the fixed support is changed to its other position and the screw replaced. The hook arm is now projecting. The handset has a cavity adjacent the receiver portion for receiving the hook arm. When the handset is placed on the vertically mounted base, the hook arm is received in the cavity in the handset to retain the handset in position, and those portions of the handset on either side of the cavity engage the two cam-shaped plungers and press them inwardly to operate the switching mechanism. It will be seen that the changing of the telephone set from a desk to a wall unit requires the use of a screwdriver and the removal and reinstalling of a part at the edge of or adjacent the depression for receiving the receiver portion of the handset.
Another prior art telephone set is described in U. S. Pat. No. 4,395,591-Kaczcos, issued Jul. 26, 1983. The base of the telephone set has depressions to receive the receiver portion and the transmitter portion of the handset. A T-shaped retainer is mounted by a screw to the base adjacent the depression for receiving the receiver portion of the handset. The stem part of the T-shaped retainer is inclined so that the inclined stem part lies in and is substantially flush with the surface of the depression for receiving the receiver portion of the handset when the telephone set is used as a desk unit. When the telephone set is used as a wall unit, the screw is removed and the T-shaped retainer is reversed so that the inclined stem part projects and the screw is replaced. The projecting stem part fits into a cavity in the handset to retain the handset when the base is mounted on a wall. It will be seen that a screwdriver is required to convert the telephone from a desk unit to a wall unit and vice versa. Also a part adjacent the depression for receiving the receiver portion of the handset must be removed and replaced.
A further U.S. Pat. No. 4,768,225-Bloechl et al, issued Aug. 30, 1988, describes another from of telephone set capable of being used as a desk or a wall unit. In the arrangement disclosed in this prior patent, a filler or retainer is received in an opening in the base of a telephone set at the edge of a depression for receiving the receiver portion of the handset. This filler clips into its opening. The filler is removable and may be inserted in one of two positions. In one position the filler is flush with the edge of the depression for receiving the receiver portion of the handset. This position is suitable for using the telephone set as a desk unit. In the other position a wedge shaped part of the filler projects beyond the edge of the depression for receiving the receiver portion of the handset. In this position the wedge shaped part engage the receiver portion of the handset and retains the handset when the base is mounted on a wall. While the arrangement disclosed in this patent does not require a tool to change from a desk unit to a wall unit, it does require that a part be removed, reversed and re-installed.
Telephone sets that require a part to be removed and replaced provide an opportunity for losing or misplacing the part. The part must be removed and re-installed by the subscriber or user when converting or changing the set from a desk unit to a wall unit, and it is preferable to avoid this. This conversion is more complex than it need be.
An object of the present invention is to provide a simpler means of converting a telephone set from a desk unit to a wall unit and vice versa.
It is another object of the invention to provide a telephone set which may be used either as a desk unit or a wall unit and may be changed from one to the other without the removal or installation of any handset retaining parts.